1. Field of the Invention
The present invention relates to a mirror actuator that turns a mirror around two shafts as turning axes and a beam irradiation device equipped with such a mirror actuator.
2. Disclosure of Related Art
In recent years, laser radars have been mounted on family cars and others for enhancement of driving safety. The laser radar generally scans a target area with laser light and detects the presence or absence of any obstacle at each scan position, depending on whether there is any reflected light at each scan position. In addition, the laser radar detects a distance from an obstacle, based on an amount of time required between the instant when laser light is irradiated and the instant when reflected light is received at each scan position. The laser radar is provided with an actuator for scanning a target area with laser light.
Such an actuator may be a mirror actuator that turns a mirror around two shafts as turning axes, for example. On the mirror actuator, laser light enters the mirror in an oblique direction. When the mirror is turned horizontally and vertically around the two shafts as turning axes, the laser light is distributed horizontally and vertically in a target area.
Such a mirror actuator has clearances parallel to the two turning axes between the two turning axes and support sections supporting the turning axes. Accordingly, even if the support sections are deformed by heat or the like, it is possible to avoid the support section from being strongly pressed against the ends of the turning axes. This allows the turning axes to turn stably.
However, if these clearances are provided, when the mirror is driven and turned, the ends of the turning axes move toward the support sections and collide against the support sections. On the laser radar, the mirror turns at a high speed and in a short cycle, and therefore the turning axes repeatedly collide against the support sections in a short cycle while the mirror is driven. The repeated collisions generate noise. In addition, the collisions make small repeated impacts on the actuator, which may deteriorate the properties of the actuator.